The present invention relates generally to disk drives, and more particularly to load beams in magnetic head suspension assemblies.
With the advent of more powerful computers and the rapid growth in the personal computer market it has become increasingly more important to enable a user to access data from storage devices with increased speed and accuracy. There is also an increasing demand for larger storage capacities in smaller package sizes.
In order to reduce access times to enable rapid retrieval of data, it is important to reduce undesirable levels of vibration of components within the rigid disk drive, and particularly within the head suspension assembly (HSA). The head suspension assembly (HSA) is a component within a disk drive which positions a magnetic read/write head over the storage media where information is to be retrieved or transferred. HSA's are mounted on rigid rotatable actuator arms and include load beams which support flexures on which the read/write heads are attached. Vibrations in the HSA can cause instability of the drive's servo system. It also may delay the transfer of data because the data can not be confidently transferred until the vibration has substantially decayed.
According to the dynamic characteristics of hard disk drive servo systems, higher vibration amplitudes or gains are more acceptable at higher frequencies--specifically, at frequencies well beyond the sampling frequency of the servo system. Increases in load beam lateral stiffness increase the frequency of vibrations beyond the servo frequency range.
Conventionally available magnetic head suspension assemblies have load beams with rails formed on the sides of the beam and extending either from the surface of the beam supporting the flexure and thus towards the disk, these rails being known as "reverse" rails, or extending from the opposite side of the beam and away from the disk, these rails being referred to as "upswept" rails.
The conventional "upswept" rail can be formed such that the rails converge at the tip of the beam on the surface opposite the flexure. This rail configuration provides advantageous lateral stiffness of the beam; however, in multiple disk drive applications, disk spacing must be maintained such that the rails (which are facing each other) on back-to-back head suspension assemblies do not interfere. This disk spacing requirement is deleterious to the goal of achieving higher data densities in smaller disk drive packages.
The conventional "reverse" rails cannot be formed to provide the same degree of convergence as the "upswept" rails because as the "reverse" rails converge toward the flexure tip, they will tend to interfere with the flexure. The "reverse" rails do not therefore provide the same advantageous degree of stiffness as the "upswept" rails. The "reverse" rail design does however allow closer inter-disk spacing due to the lack of interference between the rails of back-to-back suspensions. Increasing the height of the "reverse" rails provides added stiffness, but causes an interference problem between the beam and the disk surface; and is again counter to data density and smaller packaging goals.
One prior art load beam combines these two rail designs to provide a load beam having rails which are essentially of the "reverse" style at the flexure tip of the beam, but of the "upswept" style at the proximal end of the beam connected to the actuator arm. However, this configuration incorporates the problems of both the prior designs. The "reverse" rails at the tip of the beam cannot be provided with an advantageous degree of convergence due to interference with the flexure. Moreover, the "upswept" rails at the proximal end of the beam promote interference between back-to-back suspensions, thus preventing close disk spacing.